The present invention relates to a mobile crane having at least two crane booms which are connected together by a joint such that the angular position with respect to each other can be adjusted, and having at least one hose passing between the crane booms. The hose is exposed in the region of the joint in at least one angular position of the crane booms.
A mobile crane of that type is disclosed in EP 1 580 159 B1. As accurately stated in paragraph 2 of that document, such mobile cranes have at least one first crane boom in the form of a crane pillar and a second crane boom in the form of a hoist boom. The crane pillar is normally mounted on a support frame which is fastened to the vehicle chassis. The crane pillar is rotatably mounted about a vertical axis with respect to the support frame. The hoist boom is mounted via the joint connecting the two crane booms such that the angular position about a horizontal axis can be adjusted. Most cranes additionally have a further crane boom which is mounted on the hoist boom via a joint such that the angular position can be adjusted (about a horizontal axis) which is usually termed the jointed boom. A jib can also be mounted in the jointed boom; this latter may have a plurality of jib extensions.
The angular adjustment of the at least two crane booms is usually carried out via hydraulically driven piston cylinder mechanisms the hydraulics of which employ a plurality of hoses which have to be guided through the mobile crane. The various possible types of hose guides are described in detail in paragraph 2 of EP 1 580 159 B1 and thus do not need to be reiterated here.
In order to prevent uncontrolled bulges or loops of the hoses from being formed in the region of the joint, which in extreme cases could result in damage to the hoses, EP 1 580 159 B1 discloses an approximately U-shaped hose guide arranged in the region of the joint which can be aligned by means of a separate hydraulic adjustment mechanism with a changed angular position of the crane booms connected via the joint.
The problem with that device is that it is relatively difficult to install because of the range movement of the crane arms. In addition, in order to be adjusted to a different angular position of the crane booms, the U-shaped hose guide must be carried separately.
U.S. Pat. No. 5,806,313 discloses a hose guide arrangement consisting of a flexible material that is fixed between two pins, with one pin on each of the two crane booms. If the angular position of the two crane booms changes with respect to each other, the flexible hose guide arrangement is stretched or compressed in order to accommodate the changed distance between the two pins.
The problem with that construction is that it is relatively bulky, since relatively long pins are required which thus project out a long distance from the crane boom so that the flexible hose guide arrangement can be placed under sufficient tension.